Method for fabricating electronic component and electro-plating apparatus

ABSTRACT

A method for fabricating an electronic component according to an Embodiment, includes a seed film forming process and an electro-plating process. In the seed film forming process, a seed film is formed above a substrate. In the electro-plating process, electro-plating is performed by soaking the seed film in a plating solution in a plating bath to which the plating solution being bubbled by a nitrogen gas is supplied, using the seed film as a cathode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2010-128060 filed on Jun. 3, 2010 in Japan, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a method for fabricating an electronic component and an electro-plating apparatus.

BACKGROUND

In recent years, with higher integration and higher performance of semiconductor integrated circuits (LSI), new microprocessing technologies have been developed. Particularly recently, replacement of aluminum (Al) alloys as a conventional wire material by low-resistant copper (Cu) or Cu alloys (that is, copper-containing materials and hereinafter, collectively referred to as Cu) is under way to achieve faster LSIs. However, it is difficult to microprocess Cu by the dry etching method such as RIE (reactive ion etching) used frequently to form an Al-alloy wire. Therefore, the so-called damascene method by which an embedded wire is formed by depositing a Cu film on a grooved dielectric film and removing the Cu film excluding the Cu film embedded in the groove by the chemical mechanical polishing (CMP) method is mainly adopted. The Cu film is generally formed by first forming a thin Cu seed film by the sputter process or the like and then forming a laminated film of a thickness on the order of several hundred nm by the electro-plating method. Further, when a multilayer Cu wire is formed, particularly the wire formation method called a dual damascene structure can also be used. According to the method, a dielectric film is formed on a lower-layer wire to form a predetermined via hole and a trench (wire groove) for an upper-layer wire and then, Cu to be the wire material is embedded in the via hole and the trench simultaneously and further, unnecessary Cu in the upper layer is removed by the CMP method for planarization to form an embedded wire.

A Cu seed film formed by the sputter process has particularly a thin side wall and is easily dissolved by a plating solution. If an attempt is made to perform electro-plating on a portion where the Cu seed film has dissolved, no Cu film is formed because no current flows. Thus, even if a Cu film grown from therearound is completely embedded in such a portion, there is a problem that the portion has poor adhesion between the side wall and the Cu film, causing defects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing principal parts of a method for fabricating a semiconductor device according to a first embodiment;

FIGS. 2A to 2C are process sectional views showing processes performed conforming to the flow chart in FIG. 1;

FIGS. 3A to 3C are process sectional views showing processes performed conforming to the flow chart in FIG. 1;

FIG. 4 is a conceptual diagram exemplifying the configuration of a plating apparatus in which a substrate is held in a standby position according to the first embodiment;

FIG. 5 is a conceptual diagram exemplifying the configuration of the plating apparatus in which the substrate is held in a plating position according to the first embodiment;

FIG. 6 is a process sectional view showing a process performed conforming to the flow chart in FIG. 1;

FIG. 7 is a diagram showing a relationship between the number of defects and an etching rate according to the first embodiment;

FIGS. 8A and 8B are conceptual diagrams of a substrate section illustrating an effect of N₂ bubbling according to the first embodiment;

FIG. 9 is a flow chart showing principal parts of the method for fabricating a semiconductor device according to a second embodiment;

FIG. 10 is a conceptual diagram exemplifying the configuration of the plating apparatus in which the substrate is held in the standby position according to the second embodiment;

FIG. 11 is a conceptual diagram exemplifying the configuration of the plating apparatus in which the substrate is held in the plating position according to the second embodiment; and

FIGS. 12A and 12B are conceptual diagrams exemplifying a technique for putting the substrate into a plating bath according to a third embodiment.

DETAILED DESCRIPTION First Embodiment

A method for fabricating an electronic component according to an Embodiment, includes a seed film forming process and an electro-plating process. In the seed film forming process, a seed film is formed above a substrate. In the electro-plating process, electro-plating is performed by soaking the seed film in a plating solution in a plating bath to which the plating solution being bubbled by a nitrogen gas is supplied, using the seed film as a cathode.

An electro-plating apparatus according to an Embodiment, includes a holder, a plating bath, a supply tank, a nitrogen gas supply unit, and a current supply device. The holder is configured to hold a substrate to be plated. An anode member is arranged in the plating bath. The supply tank is configured to supply a plating solution being bubbled by a nitrogen gas to the plating bath. The nitrogen gas supply unit is configured to supply the nitrogen gas into the supply tank. The current supply device is configured to pass a current between the substrate to be plated and the anode member.

In the first embodiment, a case where a Cu damascene wire is formed in an insulating layer of a low-k film will be described below using the drawings.

FIG. 1 is a flow chart showing principal parts of a method for fabricating a semiconductor device according to the first embodiment. In FIG. 1, in the present embodiment, a series of processes is performed, including a low-k film formation process that forms a thin low-k film made of a low dielectric constant material (S102), a cap film formation process that forms a cap film (S104), an opening formation process that forms an opening (S106), a barrier metal film formation process (S108), a seed film formation process (S110), a nitrogen (N₂) bubbling and electro-plating process (S114), and a polishing process (S116).

FIGS. 2A to 2C are process sectional views showing processes performed conforming to the flow chart in FIG. 1. FIGS. 2A to 2C show the low-k film formation process (S102) to the opening formation process (S106) in FIG. 1. Subsequent processes will be described later.

In FIG. 2A, as the low-k film formation process (S102), a thin film of a low-k film 220 using a porous low dielectric constant material is formed on a substrate 200 as an example of a base substance to a thickness of, for example, 300 nm. By forming the low-k film 220, an inter-level dielectric whose relative dielectric constant k is 3.0 or less can be obtained. Porous silicon oxycarbide (SiOC) is suitably used as a material of the low-k film 220. Using a porous SiOC film, an inter-level dielectric whose relative dielectric constant k is, for example, 2.6 or less can be obtained. As a formation method thereof, for example, the PECVD method can be used. For example, a mixed gas including methyl-di-ethoxy-silane, alpha-terpinene (C₁₀H₁₆), oxygen (O₂), and helium (He) is caused to flow into a chamber (not shown), the substrate 200 is heated to, for example, 250° C. while pressure inside the chamber is maintained at 1.3×10³ Pa (10 Torr) or less, and high-frequency power is supplied to a lower electrode and an upper electrode (not shown) in the chamber to generate plasma. Methyl-di-ethoxy-silane is a gas for forming main skeleton components and alpha-terpinene is a gas for forming porogen. Then, porogen contained in the SiOC film is removed by heating and vaporizing porogen. Then, in a nitrogen atmosphere, the SiOC film is cured by ultraviolet (UV) irradiation at, for example, 450° C., which is higher than the porogen removal temperature. Accordingly, the low-k film 220, which becomes a porous dielectric film, can be formed. The formation method is not limited to the CVD method, and the SOD (spin on dielectric coating) method by which a thin film is formed by spin-coating and heat-treating a solution may also be suitably used. For example, a film having siloxane backbone structures such as polymethyl siloxane having methyl siloxane as a main component, polysiloxane, hydrogen silsesquioxane, and methyl silsesquioxane can suitably be used as a material of the low-k film 220. A ground film (not shown) is suitably formed in a lower layer of the low-k film 220. As the ground film, for example, silicon oxide (SiO₂), silicon oxycarbide (SiCN), silicon carbide (SiC), or non-porous silicon carboxide (dense SiCO) is suitable. A ground film can be formed by the PECVD method, but the formation method is not limited to this and some other method may also be used to form the ground film. The ground film of 20 nm, for example, is formed. A silicon wafer having a diameter of 300 mm, for example, is used as the substrate 200. Here, a contact plug layer and device portions are not illustrated. On the substrate 200, other metal wires or a layer having various semiconductor elements or structures (not shown) may be formed. Alternatively, some other layer may be formed.

In FIG. 2B, as the cap film formation process (S104), a thin film of an SiOC film 222 is formed on the low-k film 220 by the CVD method by depositing silicon oxycarbide (SiOC) as a cap dielectric film to a thickness of, for example, 50 nm. By forming the SiOC film 222, it becomes possible to protect the low-k film 220 to which it is difficult to directly apply lithography and to form a pattern on the low-k film 220. In addition to SiOC, at least one dielectric material selected from the group composed of silicon oxide (SiO₂), SiC, silicon carbohydrate (SiCH), silicon carbonitride (SiCN), and SiOCH and whose relative dielectric constant is 2.5 or more may be used as the material of the cap dielectric film. Here, the CVD method is used to form the cap film, but some other method may also be used.

In FIG. 2C, as the opening formation process (S106), an opening 150, which is a wire groove structure to produce a damascene wire in lithography and dry etching processes, is formed in the SiOC film 222 and the low-k film 220. A wire groove of 5 μm in width, for example, is formed. The opening 150 can be formed substantially perpendicularly to the surface of the substrate 200 by removing the exposed SiOC film 222 and the low-k film 220 positioned in the lower layer thereof from the substrate 200 having a resist film formed on the SiOC film 222 through the lithography process such as a resist coating process and exposure process, which are not shown, by the anisotropic etching method. For example, the opening 150 may be formed by the reactive ion etching method. If the above-described ground film is formed in a lower layer of the low-k film 220, the ground film may also be removed by the anisotropic etching method.

FIGS. 3A to 3C are process sectional views showing processes performed conforming to the flow chart in FIG. 1. FIGS. 3A to 3C show the barrier metal film formation process (S108) to the N₂ bubbling and electro-plating process (S114) in FIG. 1, as a conductive material film formation process. Subsequent processes will be described later.

In FIG. 3A, as the barrier metal film formation process (S108), a barrier metal film 240 using a barrier metal material is formed in the opening 150 formed by the opening formation process and on the surface of the SiOC film 222. The barrier metal film 240 is formed by depositing a thin film of a tantalum (Ta) film to a thickness of, for example, 30 nm in a sputtering apparatus using a sputter process, which is a kind of the physical vapor deposition (PVD) method. The deposition method of a barrier metal material is not limited to the PVD method, and the atomic layer deposition (ALD or the atomic layer chemical vapor deposition (ALCVD)) method or the CVD method may also be used. The coverage can thereby be made higher than when the PVD method is used. In addition to Ta, a tantalum-based tantalum-containing material such as tantalum nitride (TaN), a titanium-based titanium-containing material such as titanium (Ti) and titanium nitride (TiN), a tungsten-based tungsten-containing material such as tungsten nitride (WN), or a laminated film combining and using Ta and TaN or the like may be used as the material of the barrier metal film.

In FIG. 3B, as the seed film formation process (S110), a Cu thin film to be a cathode electrode in the next process, that is, the electro-plating process, is caused to deposit (form) on an inner wall of the opening 150 in which the barrier metal film 240 is formed and on the surface of the substrate 200 as a seed film 250 (an example of the copper-containing film) by the PVD method such as the sputter process. Here, the seed film 250 is caused to deposit, for example, on the surface of the substrate 200 to a thickness of 20 nm.

In the first embodiment, N₂ bubbling is performed before plating is started in the next process, that is, the electro-plating process (S114), to prevent the seed film 250 from disappearing after being dissolved by a plating solution, and electro-plating is performed by using the plating solution with which N₂ bubbling has been performed at least until the plating is started (the passage of electric current for electro-plating is started).

In FIG. 3C, as the N₂ bubbling and electro-plating process (S114), the seed film 250 is soaked in the plating solution in a plating bath to which the plating solution bubbled by a nitrogen gas is supplied, to cause a Cu film (example of copper-containing film) 260 to deposit in the opening 150 and on the surface of the substrate 200 by the electrochemical growth method based on electro-plating using the seed film 250 as a cathode. Here, the Cu film 260 of the thickness of, for example, 800 nm is caused to deposit, and which annealing is performed, for example, at 150° C. for 30 min.

FIG. 4 is a conceptual diagram exemplifying the configuration of a plating apparatus in which a substrate is held in a standby position according to the first embodiment. In the electro-plating apparatus, an N₂ tank 620 (nitrogen gas supply unit), a nozzle 632, a supply tank 610, a plating bath 650, an anode electrode 654, a current supply device 612, and a holder 652 are arranged. A nitrogen (N₂) gas supplied from the N₂ tank 620 is supplied (discharged) into a plating solution 670 from the tip of the nozzle 632 extending into the plating solution 670 inside the supply tank 610 via a valve 630 and a pipe 631. Then, a portion of the N₂ gas is dissolved in the plating solution 670 and the rest thereof is discharged into the air from above. Thus, in the supply tank 610, the plating solution 670 is bubbled by the N₂ gas. Then, as described above, the plating solution 670 bubbled by the N₂ gas is supplied to the plating bath 650 by a pump 640. Moreover, the plating solution 670 continues to be supplied to the plating bath 650 by the pump 640 since electro-plating is started until the plating is completed. The plating solution 670 overflowing from the plating bath 650 is returned to the supply tank 610 by going through a pipe. Therefore, the plating solution 670 circulates through the supply tank 610 and the plating bath 650. In other words, the plating solution 670 supplied to the plating bath 650 continues to be bubbled by the N₂ gas inside the supply tank 610 since before electro-plating is started until electro-plating is completed. Then, the plating solution 670 continuing to be bubbled inside the supply tank 610 circulates between the supply tank 610 and the plating bath 650 since before electro-plating is started until electro-plating is completed. Therefore, the plating solution 670 overflowing from the plating bath 650 is bubbled by the N₂ gas inside the supply tank 610 and then supplied to the plating bath 650 again. A solution obtained by adding an additive to a solution containing copper sulfate as a main component may be used as the plating solution 670. The plating bath 650 is formed in a substantially cylindrical shape and contains therein the plating solution 670 supplied from the supply tank 610. At the bottom of the plating solution 670 in the plating bath 650, the anode electrode 654 made of an anode member whose upper surface is exposed to the plating solution 670 is arranged. As the anode electrode 654, for example, a soluble anode such as phosphorous-containing copper may be used. The holder 652 is arranged above the plating bath 650 to removably hold the substrate 200 whose plating surface faces downward. The current supply device 612 passes a current to between the anode electrode 654 and the substrate 200 to be a substrate to be plated.

In FIG. 4, a state in which the holder 652 holds the substrate 200 in a position raised from the liquid surface of the plating solution 670 is shown. For example, the substrate 200 is held in a standby position for transportation by a robot or the like (not shown). A cathode contact plug is connected to an outer circumferential portion of the surface of the substrate 200 where the seed film is formed in a region that does not come into contact with the plating solution 670. On the other hand, an anode contact plug is connected to the anode electrode 654. Facilities before the N₂ gas is supplied to the supply tank 610, for example, the N₂ tank 620, the valve 630, the pipe 631, and the nozzle 632 may be arranged as supply facilities on the side of the user, instead of components constituting the electro-plating apparatus.

FIG. 5 is a conceptual diagram exemplifying the configuration of the plating apparatus in which the substrate is held in a plating position according to the first embodiment. In the first embodiment, when the surface of the substrate 200 is put into the plating bath 650 filled with the plating solution 670, the substrate 200 is put into the plating bath 670 being bubbled by an N₂ gas while rotating the substrate 200 using the holder 652. Accordingly, the seed film 250 is soaked in the plating solution 670 in the plating bath 650 to which the plating solution 670 being bubbled by the N₂ gas is supplied. By soaking the seed film 250 in the plating solution 670 being bubbled by the N₂ gas, dissolution of the seed film 250 can be suppressed. To suppress dissolution of the seed film 250, the plating solution 670 N₂-bubbled at least until electro-plating is started since before electro-plating is started (before the substrate is put into the plating solution) is supplied to the plating bath 650. Then, the surface of the substrate 200 is soaked in the plating solution 670 while rotating the substrate 200 and a current of a predetermined current density is passed from the current supply device 612 with the anode electrode 654 set as an anode and the seed film 250 of the substrate 200 to be a plating surface set as a cathode to perform electro-plating. When the substrate 200 is put into the plating solution 670, it is better to tilt the substrate by a predetermined angle so that no air is left between the substrate 200 and the plating solution 670.

Then, a damascene wire is formed by removing, using CMP, the Cu film 260 and the barrier metal film 240 that are deposited on the opening 150 and excessive from the above state.

FIG. 6 is a process sectional view showing a process performed conforming to the flow chart in FIG. 1. In FIG. 6, the polishing process (S116) in FIG. 1 is shown.

In FIG. 6, as the polishing process, the surface of the substrate 200 is polished by the CMP method and the Cu film 260 including the seed film 250 to be a wiring layer as a conductive portion deposited on the surface other than the opening and the barrier metal film 240 are polished and removed for planarization as shown in FIG. 6. In this manner, the damascene wire can be formed.

FIG. 7 is a diagram showing a relationship between the number of defects and an etching rate according to the first embodiment. In FIG. 7, the etching rate shows the rate of dissolution of Cu into the plating solution. The number of defects shows the number of poorly embedded wires after polishing. The etching rate can be decreased by performing N₂ bubbling. Then, by decreasing the etching rate, dissolution of the seed film 250 can be suppressed and also a region without the seed film 250 can be prevented. As a result, poorly embedded wires can be reduced.

The reason why the rate of dissolution of Cu can be reduced by performing N₂ bubbling is considered to be because Cu dissolution in the plating solution occurs according to the following reaction formula:

Cu+O₂+2H⁺→Cu²⁺+H₂O

Cu reacts with dissolved oxygen and acid in the plating solution to elute into the plating solution. Dissolved oxygen in the plating solution is expelled by performing N₂ bubbling so that the amount of reaction of the above reaction formula decreases. Accordingly, elution of Cu into the plating solution can be considered to have decreased.

FIGS. 8A and 8B are conceptual diagrams of a substrate section illustrating an effect of N₂ bubbling according to the first embodiment. If no N₂ bubbling is performed, as shown in FIG. 8A, voids arise due to losses of the seed Cu film that conspicuously occur on the side wall of the opening. By contrast, as described above, by putting the substrate into the N₂-bubbled plating solution 670, as shown in FIG. 8B, incomplete plating due to losses of seed Cu film that conspicuously occur particularly on the side wall of the opening can be prevented by suppressing dissolution of the seed Cu film before plating.

When electro-plating is performed, the seed film 250 may further be put into the plating bath 650 filled with the plating solution 670 in a state in which a voltage is applied to the seed film 250 from the current supply device 612 while performing N₂ bubbling. Particularly in the first embodiment, a voltage lower than a voltage when electro-plating is started after the substrate is soaked in the plating solution 670 is suitably applied to the seed film 250 when the substrate is put into the plating bath 650 filled with the plating solution 670. With this configuration, dissolution of the Cu seed film can further be suppressed.

To completely prevent dissolution of the Cu seed film without performing N₂ bubbling, it is necessary to set the voltage at which Cu plating occurs. However, when the substrate is put into the plating bath 650, it takes a predetermined time before the whole surface of the substrate 200 comes into contact with the plating solution 670 and the plating time is different between a portion that comes into contact with the solution first and a portion that comes into contact last, resulting in degradation in embedding uniformity of the Cu film 260 grown as plating on the surface of the substrate 200. Moreover, if the voltage applied to the substrate 200 is decreased without performing N₂ bubbling, incomplete plating or defects occur on the side wall where the Cu seed film is thin. Therefore, in the first embodiment, a voltage lower than a voltage when electro-plating is started after the substrate is put into the plating bath 650 filled with the plating solution 670 is applied to the seed film 250 when the substrate is soaked in the plating solution 670 while performing N₂ bubbling. Accordingly, dissolution of the Cu layer can be suppressed while maintaining embedding uniformity.

Second Embodiment

In the second embodiment, a case where, in addition to content in the first embodiment, the substrate is further cooled will be described below using the drawings.

FIG. 9 is a flow chart showing principal parts of the method for fabricating a semiconductor device according to the second embodiment. In the present embodiment, FIG. 9 is the same as FIG. 1 except that a cooling process (S112) is added between the seed film formation process (S110) and the N₂ bubbling and electro-plating process (S114). Other than content described below are the same as in the first embodiment. Each process up to the seed film formation process (S110) is the same as in the first embodiment.

The seed film 250 is cooled as the cooling process (S112). The rear surface of the substrate 200 is cooled by using a gas as a cooling method to cool the seed film 250 via the rear surface of the substrate 200.

FIG. 10 is a conceptual diagram exemplifying the configuration of the plating apparatus in which the substrate is held in the standby position according to the second embodiment. In FIG. 10, the holder 652 is worked out so that a space is formed on the rear surface side of the substrate 200 and the space serves as a channel 601 of a gas. A portion of a nitrogen (N₂) gas supplied from the N₂ tank 620 is supplied to the supply tank 610 via the valve 630, the pipe 631, and a pipe 634 and the rest thereof to the channel 601 of the holder 652 via the valve 630, the pipe 631, and a pipe 636. By causing the N₂ gas to flow to the rear surface of the substrate 200 held in the standby position, the substrate temperature is controlled. By passing the N₂ gas through the channel 601 in this manner, the rear surface of the substrate 200 is cooled. The silicon wafer as the substrate 200 has high thermal conductivity and thus, the substrate temperature can be cooled to a temperature comparable to the gas temperature by causing the gas to flow to the rear surface of the substrate 200 for a sufficiently long time. Other portions of the configuration are the same as in FIG. 4. Thus, the seed film 250 is cooled by cooling the rear surface of the substrate 200 using the N₂ gas supplied from the N₂ tank 620, which is the same supply source as the N₂ gas used for bubbling.

It is preferable that the substrate be cooled to a temperature cooler than the temperature of the plating solution 670 by 10° C. or more. If, for example, the temperature of the plating solution 670 is 25° C., the substrate temperature may be controlled to a range between a temperature at which condensation of the substrate 200 is not caused (for example, 5° C.) and 15° C. If the rate of dissolution of the seed film 250 in the plating solution 670 at 25° C. is 100%, the rate of dissolution of the seed film 250 in the plating solution 670 can be suppressed to 56% by cooling the substrate temperature to 15° C. If the substrate temperature is cooled to 5° C., the rate of dissolution of the seed film 250 in the plating solution 670 can be suppressed to about 30%. That is, by cooling the substrate temperature to 15° C. or below, the rate of dissolution can be reduced to almost the half. The cooling position is preferably as close to the plating solution 670 as possible. By making the cooling position as close to the plating solution 670 as possible, the time necessary for the substrate 200 to come into contact with the plating solution 670 after the cooling can be reduced to maintain the cooling effect.

In FIG. 3C, as the N₂ bubbling and electro-plating process (S114), the seed film 250 cooled by the N₂ gas is soaked in the plating solution in the plating bath 650 to which the plating solution 670 bubbled by the N₂ gas is supplied, to perform electro-plating using the seed film 250 as a cathode. In this case, control is exercised so that the N₂ tank 620 continues to supply the N₂ gas at least since before electro-plating is started (before the substrate is put into the plating solution) until when electro-plating is started. Further, the N₂ tank 620 may continue to supply the N₂ gas since before electro-plating is started (before the substrate is put into the plating solution) until electro-plating is completed.

FIG. 11 is a conceptual diagram exemplifying the configuration of the plating apparatus in which the substrate is held in the plating position according to the second embodiment. In the second embodiment, when the surface of the substrate 200 is put into the plating bath 650 filled with the plating solution 670 being N₂-bubbled, the substrate 200 whose seed film 250 has been cooled by the above cooling process is put into the plating bath 670 while rotating the substrate 200. Then, the surface of the substrate 200 is soaked in the plating solution 670 while rotating the substrate 200 and a current of a predetermined current density is passed from the current supply device 612 with the anode electrode 654 set as an anode and the seed film 250 of the substrate 200 to be a plating surface set as a cathode to perform electro-plating. As described above, when the substrate 200 is put into the plating solution 670, it is better to tilt the substrate by a predetermined angle so that no air is left between the substrate 200 and the plating solution 670.

When electro-plating is performed, the cooled seed film 250 may further be put into the plating bath 650 filled with the plating solution 670 (soaked into the plating solution 670 from outside the plating solution 670) in a state in which a voltage is applied to the seed film 250 from the current supply device 612 while performing N₂ bubbling. As described above, a voltage lower than a voltage when electro-plating is started after the substrate is put into the plating bath 650 filled with the plating solution 670 is suitably applied to the seed film 250 when the substrate is soaked in the plating solution 670 (soaked into the plating solution 670 from outside the plating solution 670).

Thus, as described above, by cooling the substrate in addition to N₂ bubbling for the plating solution 670, when the surface of the substrate 200 is put into the plating bath 650, dissolution of the seed film 250 can further be suppressed.

Third Embodiment

In the second embodiment, before the substrate 200 is put into the plating bath 650, for example, the substrate 200 is cooled in the standby position shown in FIG. 10 and cooling is stopped when the substrate 200 is put into the plating bath 650, but the present embodiment is not limited to this.

FIGS. 12A and 12B are conceptual diagrams exemplifying a technique for putting the substrate into a plating bath according to a third embodiment. As shown in FIG. 12A, like in the second embodiment, the N₂ gas supplied from the N₂ tank 620 is caused to flow while touching the rear surface of the substrate 200 before the substrate 200 is put into the plating bath 650. In the third embodiment, as shown in FIG. 12B, the substrate 200 is put into the plating bath 650 while being cooled. With this configuration, the cooling effect can better be maintained. Moreover, it is allowed to continue to cool the substrate 200 during actual plating.

According to the above embodiments, as described above, occurrences of incompletely plated films after electro-plating and defects can be reduced while suppressing dissolution of a seed film.

In the foregoing, the embodiments have been described with reference to concrete examples. However, the embodiments are not limited to such concrete examples. In the above embodiments, the low-k film 220 is used as a dielectric film, but the dielectric film is not limited to the low-k film 220 and other insulating materials may also be used. For example, a silicon oxide (SiO₂) film may be used. The rear surface of the substrate 200 may indirectly be cooled, instead of cooling directly. The embodiments describe a damascene wire, but a dual damascene wire can also achieve similar effects. Particularly, the embodiments are suitable for Cu embedding in a via hole in dual damascene wire formation. In the above examples, the N₂ gas supplied from the N₂ tank 620 is branched to the holder 652 side and the supply tank 610 of the plating solution, but the embodiments are not limited to such examples. For example, the N₂ gas after being supplied to the holder 652 side and discharged from the holder 652 may be supplied to the supply tank 610 for N₂ bubbling.

Concerning the thickness of inter-level dielectrics and the size, shape, number and the like of openings, what is needed for semiconductor integrated circuits and various semiconductor elements can be selected and used as appropriate.

In addition, methods for fabricating an electronic component represented by all methods for fabricating a semiconductor device including the elements of the embodiments and obtainable by arbitrarily changing the design by a person skilled in the art are included in the scope of the embodiments.

While techniques normally used in the semiconductor industry such as a photolithography process and cleaning before and after treatment are not described for convenience of description, it is needless to say that such techniques are included in the scope of the embodiments.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and devices described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and devices described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. 

1. A method for fabricating an electronic component, comprising: forming a seed film above a substrate; and performing electro-plating by soaking the seed film in a plating solution in a plating bath to which the plating solution being bubbled by a nitrogen gas is supplied, using the seed film as a cathode.
 2. The method according to claim 1, further comprising: cooling the seed film by supplying a nitrogen gas to a rear surface of the substrate from a same supply source as the nitrogen gas used for a bubbling.
 3. The method according to claim 2, wherein the nitrogen gas after being supplied to the rear surface of the substrate is used for the bubbling of the plating solution.
 4. The method according to claim 1, wherein when the electro-plating is performed, the seed film is soaked in the plating solution from outside the plating solution in a state in which a voltage is applied to the seed film.
 5. The method according to claim 1, wherein a voltage lower than a voltage when the electro-plating is started after the seed film is soaked in the plating solution is applied to the seed film when the seed film is soaked in the plating solution from outside the plating solution.
 6. The method according to claim 1, wherein the seed film is formed by using copper (Cu).
 7. The method according to claim 1, wherein the plating solution supplied to the plating bath continues to be bubbled by the nitrogen gas since before the electro-plating is started at least until when the electro-plating is started.
 8. The method according to claim 1, wherein the plating solution supplied to the plating bath continues to be bubbled by the nitrogen gas since before the electro-plating is started until the electro-plating is completed.
 9. The method according to claim 1, further comprising: bubbling the plating solution inside a supply tank by the nitrogen gas; and supplying the plating solution that continues to be bubbled inside the supply tank to the plating bath.
 10. The method according to claim 9, wherein the plating solution that continues to be bubbled inside the supply tank circulates through the supply tank and the plating bath since before the electro-plating is started until the electro-plating is completed.
 11. The method according to claim 9, wherein a portion of the plating solution overflowing from the plating bath is bubbled inside the supply tank by the nitrogen gas and then supplied to the plating bath again.
 12. An electro-plating apparatus, comprising: a holder configured to hold a substrate to be plated; a plating bath in which an anode member is arranged; a supply tank configured to supply a plating solution being bubbled by a nitrogen gas to the plating bath; a nitrogen gas supply unit configured to supply the nitrogen gas into the supply tank; and a current supply device configured to pass a current between the substrate to be plated and the anode member.
 13. The apparatus according to claim 12, wherein the holder has a channel, through which a nitrogen gas supplied from the nitrogen gas supply unit passes while the substrate to be plated is held, formed in a rear surface side of the substrate held.
 14. The apparatus according to claim 13, wherein the rear surface of the substrate to be plated is cooled by the nitrogen gas being passed through the channel.
 15. The apparatus according to claim 12, wherein a seed film is formed on the substrate to be plated, and the seed film is soaked into the plating solution from outside the plating solution by the holder in a state in which a voltage is applied to the seed film by the current supply device.
 16. The apparatus according to claim 15, wherein the current supply device applies a voltage, lower than the voltage when electro-plating is started after the seed film is soaked in the plating solution, to the seed film when the seed film is soaked into the plating solution from outside the plating solution.
 17. The apparatus according to claim 15, wherein the nitrogen gas supply unit is controlled to continue to supply the nitrogen gas into the supply tank since before the seed film is soaked in the plating solution at least until when electro-plating is started.
 18. The apparatus according to claim 15, wherein the nitrogen gas supply unit is controlled to continue to supply the nitrogen gas into the supply tank since before the seed film is soaked in the plating solution until the electro-plating is completed.
 19. The apparatus according to claim 12, further comprising: a mechanism configured to cause the plating solution continuing to be bubbled by the nitrogen gas inside the supply tank to circulate between the supply tank and the plating bath since before electro-plating is started until the electro-plating is completed.
 20. The apparatus according to claim 19, wherein a portion of the plating solution overflowing from the plating bath is bubbled inside the supply tank by the nitrogen gas and then supplied to the plating bath again. 